This invention relates generally to X-ray tables and more particularly to apparatus for leveling spot film devices for X-ray tables.
As is known, a conventional X-ray table comprises a table body having a top surface and supporting a tower. The tower is supported on guide tracks on the table so that the tower may slide along the longitudinal axis of the table. The tower typically is equipped with vertical guide tracks along which a carriage is slidably mounted. Bearings carried by the carriage allow the carriage to move vertically along the tower tracks. The purpose of the carriage is to provide support for a spot film device. The spot film device projects over the table and is equipped with a set of horizontal tracks which engage a set of bearings within the carriage. Thus, the spot filmer can be displaced horizontally along the transverse axis of the table.
In order for the X-ray table to perform properly, the spot film device must be level with respect to the table. That is, the spot film device and the table surface must lie in parallel planes. The spot film device must, therefore, be disposed parallel to both the longitudinal and transverse axes of the table. One apparatus used in the art provides leveling along the transverse axis by permitting adjustment of the position of the carriage bearings engaged by the spot film device. Each track on the spot film device lies on two pairs of opposing bearings carried by the carriage. The position of one bearing of each of the opposing pairs of bearings is adjustable, such as by an eccentric axle. Thus, the angle at which the spot film device slides along the carrier, and hence the angle between the spot film device and the table surface may be adjusted by altering the position of the adjustable carriage bearings.
While the above-described spot film device leveling apparatus functions satisfactorily in some applications, there are problems associated therewith. First, the apparatus provides leveling with respect to the transverse axis of the table, but does not allow the spot film device to be leveled along the longitudinal axis of the table. Further, the amount of leveling adjustment that can be achieved by altering the position of the carriage bearings is limited. Thus, it is possible that tranverse leveling of very heavy spot film devices might not be achieved by the above-described prior art apparatus.